The invention relates to two-layer magnetic tapes and, more particularly, to a method and system that enable the recording and reading of such tapes in providing for a high degree of protection from errors and/or fraudulent behaviour.
More specifically, this high degree of protection from errors and/or fraudulent behaviour is obtained by seeing to it that it is no longer possible to modify the useful information without incurring a refusal during the reading of the modified information.
The invention shall be described with reference to a particular application to the recording and reading of magnetic labels carried on the packages of medicines. These magnetic labels are designed to record a number of information elements such as the pharmaceutical identification code (P.I.C.), the reimbursement ratio (under health insurance), the price etc. When a medicine is sold by a pharmacist, this magnetic label is read by a reader connected to a computer and the information elements read are processed by this computer to be entered into the accounts by the pharmacist and/or sent to the insurance organisation.
To prevent the consequences of errors and curb fraudulent behaviour, it is of prime importance that a medicine sold should not be entered into the accounts or be subject to a refund or reimbursement more than once.
The object of the invention, therefore, is to implement a method and a system for the recording and reading of magnetic labels that does not allow such errors and/or fraudulent behaviour.
To this effect, the invention proposes the use of a two-layer magnetic tape or label, one layer of which has a high coercive field while the other layer has a lower coercive field. The recording is done on these two layers in synchronism so as to record all the necessary information elements in the layer with a low coercive field and only a portion of these information elements, for example the price, in the layer with a high coercive field. When the label is read at the time of a sale, the information elements of the layer with a low coercive field are erased after a reading without error and the information elements of the layer with a high coercive field are read to be compared with the corresponding information elements read previously on the layer with a low coercive field. If the comparison reveals no error, then the information elements read on the layer with a low coercive field are validated in order to be entered into the accounts and/or forwarded to the refunding organisation. If the opposite is the case, they are considered to be erroneous or false, and are not taken into account.